Orthopedic cements, e.g., calcium phosphate cements that are prepared by combining a dry component(s) and a liquid to form a flowable paste-like material that is subsequently capable of setting into a solid calcium phosphate product hold great promise for use as structural materials in the orthopedic and dental fields. For example, it is desirable to be able to introduce a flowable material into a cancellous bone target site, e.g., as may be present in a reduced fracture, and have the material set into a solid calcium phosphate mineral product that is capable of withstanding physiological loads. Materials that set into solid calcium phosphate mineral products are of particular interest as such products can closely resemble the mineral phase of natural bone and are susceptible to remodeling, making such products extremely attractive for use in orthopedics and related fields.
As calcium phosphate cements have been refined, delivery protocols and devices for use in the same have also been developed. Where the target bone site is a porous cancellous structure, e.g., as may be encountered in a reduced fracture or inside a compromised vertebral body, one approach is to deliver the cement under high pressure, so that it adequately penetrates the cancellous bone tissue. However, a disadvantage of high pressure delivery methods is that they can result in penetration beyond the site of interest, and delivery may be hard to control, such that even when the pressure source is removed, cement still penetrates the tissue, perhaps to undesirable areas and/or causing undesirable side effects.
An alternative to delivery under pressure is to remove the cancellous tissue from the target site to produce a true void space into which the cement composition may be introduced. In certain embodiments, a void space may be produced by introducing a balloon into the target site and expanding the balloon in a manner that compresses the cancellous tissue and results in the production of a void space at the target site. However, there are disadvantages to this approach as well, such as the loss of cancellous tissue.
As such, there continues to be an interest in the development of new calcium phosphate cement delivery protocols and devices for use in practicing the same.
Relevant Literature
United States patents of interest include: U.S. Pat. Nos. 6,375,935; 6,139,578; 6,027,742; 6,005,162; 5,997,624; 5,976,234; 5,968,253; 5,962,028; 5,954,867; 5,900,254; 5,697,981; 5,695,729; 5,679,294; 5,580,623; 5,545,254; 5,525,148; 5,281,265; 4,990,163; 4,497,075; 4,429,691; 4,161,511 and 4,160,012.